The present invention relates to an insert intended to be supported on a holder and used in machining for grooving, cut-off or contouring operations; and particularly to an insert suited for deep grooving on various kinds of metals, which often poses a difficult machining problem.
In deep grooving or cut-off operations the depth of cut is large compared with the width of the cutting tool. As a result, chips tend to come out without breaking and wind around the tool or workpiece or both, causing troubles. Therefore, frequently a chip-breaking shelf is formed on the rake face of a grooving insert at a certain distance from the cutting edge with such a gradient as to cause the ejected chips to travel in a desired direction and curl or break into pieces. However, known structures fail to optimize chip breaking over a wide range of material, such as steel of high toughness and low carbon content on the one hand and low toughness and high carbon content on the other, and also over a wide range of tool feeds and cutting speeds.
For example, chips from a workpiece having a low toughness and a high carbon content tend to contact the insert at the point near the cutting edge and more readily curl and break, whereas chips from a workpiece having a high toughness and a low carbon content tend to deform plasticly to a greater extent, curl with a larger radius, and therefore do not break as readily.